In certain situations, it is desirable to have a robotic vehicle which can autonomously travel a selected path, for example, to distribute and collect mail within an office building, or to distribute to or transfer parts between work stations in a factory. Such automatic guided vehicles (AGV's) generally use a guide wire buried in the floor which carries an AC signal to be sensed by the AGV. This wire guided approach is undesirable in situations where the AC signal could interfere with adjacent equipment, such as in factories manufacturing or testing delicate electronics equipment, and in situations where it is not easy to retrofit an existing floor with a buried wire.
Another approach involves using a fluorescent paint to define a path for the AGV. While the use of a path painted or otherwise applied on the floor surface has clear advantages over a buried wire, a suitable control system must be devised. With any system utilizing a path marked on the floor, the control system must be able to detect the path and determine the lateral position of the AGV relative to the path, and able to provide an appropriate guidance signal to the AGV steering/propulsion system indicative of the lateral directional position and distance of the AGV relative to the path.
The present invention provides a control system for an AGV which utilizes minimal hardware while providing improved lateral position control, and emitting no electrical radiation such as produced by guidance signals emanating from a wire embedding in the floor. Moreover, the present invention provides a means for easy change of the path layout to accommodate changes in office and factory needs, and provides other advantages.